Field of the Invention
The present disclosure relates to at least one method for forming a pattern having a hollow structure.
Description of the Related Art
In the field of advanced devices such as semiconductor devices and microreactors, hollow structures functioning as circuits and microchannels are often formed by photolithography. In a typical manufacturing process of a hollow structure, a first micropattern having a hollow structure is first formed on a substrate, and then a second micropattern is formed on the first micropattern. In this process, when the second micropattern is exposed to light, the light may pass through the resist film for forming the second micropattern and reflect diffusely at the relief portion, or uneven portion, of the first micropattern.
The diffused reflection at the relief portion of the first micropattern causes the diffusely reflected light to irradiate a portion of the resist film that should not be exposed, thereby undesirably reducing the line width of the second micropattern. Particularly when the first micropattern includes electrodes or conductive lines, which are often made of aluminum or any other light reflective material, the amount of light reflecting from the relief portion of the micropattern is increased, and accordingly, the line width of the second micropattern tends to be reduced.
Japanese Patent Laid-Open No. 2008-229947 discloses a method for suppressing diffused reflection from the layer underlying the first micropattern. In this method, a light-absorbing layer capable of absorbing light is formed on the surface of the underlying layer, and then a resist layer is formed on the light-absorbing layer. According to this method, even if exposure light has passed through the resist layer, the light-absorbing layer absorbs the passed light, thus reducing diffused reflection from the layer under the resist layer.